The $19.5 million purchase, announced on 23 August, will be split equally between shares and cash.
Watermark employs more than 90 people, including 30 IP professionals. Xenith intends to allow Watermark to run as a standalone business and maintain its brand.
Stuart Smith, managing director of Xenith, which also owns Shelston IP, said: “Watermark holds a prominent market position within the Australian IP sector.”
“We are very excited by the opportunity to work with Watermark and its existing team to grow the combined businesses under the Xenith banner. We are particularly enthusiastic about the strength of the strategic alignment and the shared vision for future growth and development.”
Xenith hopes the deal will “diversify revenue streams, broaden its client base and enhance its geographical presence”.
Karen Sinclair, chair of Watermark, said: “We believe the combination of Xenith and Watermark will bring considerable benefits and opportunities for our clients and our respective personnel.”